US testing an 'air traffic control system' for drones

The Guardian has gained access to the first tests of an experimental air traffic control system for drones that could open the skies to millions of low-flying unmanned aircraft.

On an isolated cattle ranch in rural North Carolina – and under the watchful eye of the Federal Aviation Administration (FAA) – drone startup PrecisionHawk is putting experimental drones in the air alongside paragliders. This is the first time that human pilots have officially shared US airspace with commercial drones.

“Building technology that enables drones to fly reliably and to stay away from airports and other flying objects is stupidly difficult,” says Bob Young, CEO of PrecisionHawk. “But safety is critically important. Without safety, you don’t fly, period.”

If only that were true. The FAA is panicking, just a little bit, about the rapid increase in the number and capability of drones now available to the general public. Drone sightings by pilots in 2015 are set to triple or even quadruple from last year. The FAA estimates that 700,000 more quadcopters will be sold to Americans in the run up to Christmas, prompting a last-minute drone registration program.

Meanwhile, Google, Amazon and Facebook are developing fleets of drones to deliver packages or provide internet service from the sky. Photographers, farmers and utility companies are also pressuring the FAA to allow unmanned aircraft for their businesses. If all these drones are to flit about the cities and countryside without colliding or bumping into manned aircraft, they will need a way to automatically avoid one another.

Millions of drones to come …

The existing air traffic control system, which relies on a few, powerful radars, simply won’t work. Not only are the smallest drones almost impossible to detect, radar does not work well at low altitudes, where its signals are obscured by hills and buildings. Besides, any system of human operators could not possibly scale to accommodate the millions of drones expected in years to come.

That’s where PrecisionHawk’s Latas technology comes in, says Young. Latas, which stands for Low Altitude Traffic and Airspace Safety, is a digital air traffic control system for drones. Instead of a central radar station detecting everything in the air, each Latas-equipped aircraft reports its location, altitude, heading and speed to software in the cloud, which then automatically warns nearby drones to avoid it.

“One of our bright young engineers suggested using the text messaging system on cellphone towers,” says Young. A drone could send up to 40 SMS text messages every second, detailing its progress through the air. “It actually worked beautifully, even on primitive 2G networks that can barely maintain a voice call any more.”

However, once PrecisionHawk started working with wireless provider Verizon, which has been working on drone navigation for some time, it realised that using 4G LTE wireless data made more sense. Not only can 4G be used to send flight data to and from the cloud, Latas could also triangulate signals from multiple towers to improve the accuracy of a drone’s location from GPS.

But what about drones surveying remote fields or filming surfers far from a mobile phone tower? “The trick is redundancy,” says Young. If there’s no phone signal, Latas can switch seamlessly to the Iridium satellite phone network, available virtually worldwide. It even incorporates ADS-B broadcasts, radio signals transmitted today by manned aircraft to reduce the chance of collisions far from traditional air traffic controls.

One big problem for a networked system like Latas is that it can only avoid all accidents if every flying machine is using it. Realistically, that would mean the FAA mandating its use. It’s a question that Young doesn’t have a good answer to at the moment, except to say, “The FAA would much rather regulate around solutions that the industry brings to it than having to pick winners. We are working extremely hard to help the industry move forward as quickly as we can.”

To that end, PrecisionHawk is starting to ramp up Latas for mass manufacture. At launch, Young expects the system to range in price from a few hundred dollars for 4G chips in hobbyist drones to perhaps a few thousand for Iridium and ADS-B equipped devices. Before it can ever take to the skies, however, Latas needs testing.

‘Geofencing’ protects buildings from drones

Peering up into the stormy skies of North Carolina on an unseasonably warm November afternoon, high above me is PrecisionHawk’s Lancaster drone (“the ugliest drone in the world” admits Young) flying back and forth with a Latas chip on board, automatically surveying the muddy fields around me.

PrecisionHawk’s main business is providing data expertise to agricultural drone operators: sensors, algorithms and analysis to turn endless gigabytes of crop photos into actionable intelligence. This cornfield might need more water, perhaps, or that orchard could be suffering from a pest that needs tackling immediately.

Senior engineer Ricardo Rodriguez is sitting in front of a laptop beneath a flimsy awning. On his screen, a webpage shows the Latas interface. The Lancaster drone is at the centre of the map, with two ghostly plane icons indicating commercial jets flying far above us and to the west. Rodriguez then zooms in and sets up a virtual “geofence” around one corner of the cow field.

When the drone flies into it, Rodriguez instantly receives a text message on his phone (and on his Pebble smartwatch) alerting him to change course. Permanent geofences will be programmed into Latas to protect airfields and government buildings, and the system will also surround every aircraft with its own dynamic geofence.

“For safety, the geofence will be much bigger than the size of the vehicle, maybe 20 metres or 30 metres in diameter,” says Rodriguez. “Although if you’re flying with your friends, you may want to get closer.” PrecisionHawk hopes that Latas will be as much a social network as a safety net, with the ability to “friend” other drones in the vicinity and subscribe to their live video feeds.

When it’s not conducting programmed aerial surveys, the Lancaster drone is piloted manually by an operator sitting at another laptop. He can take control of the propeller-driven aircraft at any moment and especially during takeoff and landing. In the future, however, drones will be expected to look after themselves for hours at a time, avoiding other aircraft as they deliver parcels or scan roads for speeding motorists.

“Testing the Lancaster with an autopilot is the next big thing,” says Rodriguez. “I’m looking forward to surprising it and seeing how it reacts, to see it take control.”

That day is not far off. In fact, PrecisionHawk is laying the groundwork for it today, with a pioneering test involving a paraglider and a drone in the air simultaneously.

‘If drones came at me, I’d kick them out of the sky’

Brian Goff is a professional paraglider pilot who has worked on nature documentaries and with the US military. He brushes off concerns about sharing airspace with the Lancaster. “I couldn’t care less about that thing,” he tells me as he slips a portable Latas transceiver, about the size of a mobile phone, into a pocket of his flight suit. “If these little ones came at me, I’d just kick them out of the sky.”

The test today, which is part of the FAA’s Pathfinder program to explore the future of drone operation, is to see how long it will take the Lancaster’s operator to spot Brian as he flies over the horizon towards the drone. A paraglider has roughly the same visual and sonic footprint as a light aircraft, but is much cheaper and more flexible for testing. “It’s like a relatively complicated game of hide and seek in the air,” says Rodriguez.

Goff fires up his paraglider engine, runs, leaps and roars into the sky, swooping around the pasture as he circles higher and higher. The PrecisionHawk team ready the Lancaster for another takeoff, then suddenly fall silent. The FAA requires three miles of visibility to operate the drone, and an approaching storm has just broached this meteorological geofence.

But the tests will continue here all week. A subsequent phase in the spring will involve putting the drone and paraglider much closer together, and seeing whether Latas can reduce the time it takes for the human drone pilot to respond to an aerial intruder. Ultimately, of course, PrecisionHawk wants Latas to control the drone directly.

Meanwhile, Goff continues to circle far above us, either waiting for the storm to shift track or just enjoying his time aloft. Although his engine is clearly audible, it is surprisingly tricky to pick out the narrow paraglider wing from the clouds gathering behind him. “Even a really good human observer can’t accurately describe the position, heading and speed of an incoming aircraft,” says Rodriguez. “But Latas can.”